TODO: Create a version of this function for creating an authenticator from environment.

ReadResponseBody fully reads a response and closes it.

PolicyModePatch adds policy data and explicitly deletes policy data.

PolicyModePost appends new data to the policy.

PolicyModePut completely replaces the policy, implicitly deleting data which is not present in the new policy.

CreatedRole contains the full role ID and API key of a role which was created by the server when loading a policy.

PolicyResponse contains information about the policy update.

PolicyMode defines the server-sized behavior when loading a policy.